WO2023029572A1

WO2023029572A1 - Preparation method for aluminum nitride

Info

Publication number: WO2023029572A1
Application number: PCT/CN2022/092488
Authority: WO
Inventors: 蔡海兵; 刘卫; 刘勇奇; 李长东; 巩勤学
Original assignee: 湖南邦普循环科技有限公司; 广东邦普循环科技有限公司; 湖南邦普汽车循环有限公司
Priority date: 2021-08-31
Filing date: 2022-05-12
Publication date: 2023-03-09
Also published as: GB202318477D0; DE112022002488T5; CN113753867A; GB2621958A; CN113753867B

Abstract

The present invention relates to the field of recycling of waste lithium batteries. Disclosed is a preparation method for aluminum nitride. The preparation method comprises the following steps: adding a sodium hydroxide solution to waste positive electrode powder for reaction, and performing solid-liquid separation to obtain a sodium aluminate solution and positive electrode powder; adding acid to the sodium aluminate solution for reaction, performing solid-liquid separation, and extracting a solid phase to obtain an aluminum hydroxide precipitate; performing water washing and sieving on a negative current collector, performing solid-liquid separation, extracting a solid phase, and adding nitric acid for reaction, and performing solid-liquid separation to obtain a graphite material and copper nitrate; mixing the aluminum hydroxide precipitate with the graphite material, granulating the mixture, and then adding copper nitrate for mixing, and performing a calcination reaction to obtain aluminum nitride and copper oxide. According to the present invention, nitrogen does not need to be additionally conveyed in the aluminum nitride synthesis process, and a self-sufficiency state is always kept in the reaction process, so that the reaction is more stable, and the purity of the generated aluminum nitride is high.

Description

A kind of preparation method of aluminum nitride

technical field

The invention relates to the field of recovery and reuse of waste lithium batteries, in particular to a preparation method of aluminum nitride.

Background technique

With the promotion of national ecological and environmental protection, more and more new energy sources are emerging, especially the lithium battery industry. Due to the advantages of high energy density, high working voltage, long cycle life, and large charge-discharge rate, lithium batteries are widely used in new energy vehicles, 3C consumer products, and energy storage batteries. 3C refers to computers, communications, and consumer electronics. Electronic products The abbreviation of the three types of electronic products. With the use of lithium batteries in the later period, a large number of batteries will inevitably be scrapped, and it becomes indispensable to deal with these used lithium batteries. The existing dry process processes waste lithium batteries, and the recovered battery powder contains a large amount of valuable metals, and the investment cost for later cleaning is relatively high, and the waste residue after the existing process is directly piled up as solid waste, causing environmental pollution and waste of resources .

At present, incineration and crushing and sorting are the most commonly used methods to deal with waste lithium batteries; incineration has high energy consumption, long process and low metal recovery rate. In particular, the battery powder produced by the incineration method has high impurity content, and the post-processing cost is too high. Among them, due to the low melting point of the positive electrode current collector metal aluminum, it is easy to melt during heat treatment and will penetrate into the battery powder, making it difficult to separate valuable metals, which is not conducive to industrial production. Although the crushing and separation process is simple, the production environment is harsh, the dust is scattered, and the equipment is prone to failure. The copper-aluminum mixture of the product has a high content of nickel and cobalt, which is difficult to effectively recover and is not conducive to production. At present, in the process of preparing aluminum nitride, ammonia and aluminum are mainly directly subjected to nitriding reaction, and then crushed and classified to obtain aluminum nitride powder, or fully mixed with alumina and carbon, and then reduced in an electric furnace at 1700°C to obtain nitriding. aluminum. During the process, the metallic aluminum needs to be crushed to the micron level, which is extremely dangerous; during the reaction process, the pipeline may not be tightly sealed when nitrogen gas is filled, resulting in a violent reaction between the internal aluminum powder and the air, which is extremely unsafe and not conducive to the process Production.

Contents of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned prior art. Therefore, the present invention provides a method for preparing aluminum nitride, which combines physical and chemical methods, can meet the industrial production requirements of environmental friendliness, low energy consumption, and high resource recovery, and has a safe process and can prepare high-purity aluminum nitride .

To achieve the above object, the present invention adopts the following technical solutions:

A preparation method of aluminum nitride, comprising the following steps:

(1) adding sodium hydroxide solution to the waste positive electrode powder for reaction, solid-liquid separation, to obtain sodium metaaluminate solution and positive electrode powder;

(2) adding an acid to the sodium metaaluminate solution for reaction, separating solid and liquid to obtain aluminum hydroxide precipitation;

(3) The negative current collector is washed with water, sieved, and solid-liquid separation is taken, and the solid phase is added to react with nitric acid, and the solid-liquid separation obtains graphite material and copper nitrate;

(4) The aluminum hydroxide precipitation described in step (2) is mixed with the graphite material described in step (3) to granulate, and then the copper nitrate described in step (3) is added to mix and roast to obtain aluminum nitride and copper oxide.

Preferably, in step (1), the waste positive electrode powder is disassembled and crushed from waste lithium batteries to obtain broken positive and negative current collectors and separator paper, and then the broken positive current collectors are pyrolyzed and sieved to obtain Metal aluminum and waste cathode powder.

Further preferably, the crushing is shear crushing, and the sieve mesh aperture is selected to be 1 cm to 5 cm.

Further preferably, the pyrolysis temperature is 400-600° C., and the pyrolysis time is 0.5-1 h.

Further preferably, the sieving screen is selected from 5 to 20 mesh.

Preferably, in step (1), the mass concentration of the sodium hydroxide solution is 10-30 g/L.

Preferably, in step (1), the liquid-solid ratio of the sodium hydroxide solution and the spent positive electrode powder is 1: (1-3) L/g.

Preferably, step (1) further includes performing wet leaching of the positive electrode powder to recover valuable metals.

Preferably, in step (2), the acid is one of hydrochloric acid and nitric acid; when the acid is hydrochloric acid, after the solid-liquid separation in step (2), aluminum hydroxide precipitation and sodium chloride solution are obtained .

Further preferably, the mass fraction of the hydrochloric acid is 20-50%.

Further preferably, the sodium chloride solution is electrolyzed to produce sodium hydroxide, which is returned to step (1) for use.

More preferably, the electrolysis voltage of the sodium chloride solution is selected as 220V.

Preferably, in step (3), the liquid-solid ratio of the water washing is 1: (1-2) L/g, and the washing time is 10-30 minutes.

Preferably, in step (3), the sieve used for the sieving is 5-10 mesh.

Preferably, in step (3), the mass fraction of the nitric acid is 30-50%.

Preferably, in step (4), the mass ratio of the aluminum hydroxide to the graphite material is (2-3):(1-2).

Preferably, in step (4), the mass ratio of copper nitrate to aluminum hydroxide is (1-3):1.

Preferably, in step (4), the particle diameter of the granulated particles is 0.5-2.0 mm.

Granulation after mixing aluminum hydroxide and graphite material is more conducive to the reaction: it is because the mixed material reacts directly, and the reactants are packed tightly, which is easy to cause incomplete reaction, poor gas circulation and small contact surface; after granulation , can improve its bulkiness, large contact surface, better gas circulation, and more conducive to complete reaction.

Preferably, in step (4), the calcination is carried out in three stages, the temperature of the first stage of calcination is 200-400°C, and the time of the first stage of calcination is 0.5-2h; the temperature of the second stage of calcination is 1000-1200°C. ℃, the time of the second stage of calcination is 1~3h; the temperature of the third stage of calcination is 1400~1600℃, and the time of the third stage of calcination is 5~8h.

Preferably, in step (4), the calcination process also includes adding a catalyst for catalysis, and the catalyst is platinum wire.

The reaction equation of each step of the present invention:

1. Formation of sodium metaaluminate: 2Al+2H ₂ O+2NaOH=2NaAlO ₂ +3H ₂ ↑;

2. Formation of aluminum hydroxide without excessive hydrochloric acid: HCl+NaAlO ₂ +H ₂ O=Al(OH) ₃ ↓+NaCl;

3. Formation of copper nitrate: H ₂ NO ₃ (dilute)+Cu=Cu(NO ₃ ) ₂ +NO↑+H ₂ O;

4. Sodium chloride electrolysis reaction: 2NaCl+2H ₂ O=2NaOH+H ₂ ↑+Cl ₂ ↑(electrolysis);

5. Heating decomposition reaction of copper nitrate: 2Cu(NO ₃ ) ₂ ＝2CuO+4NO ₂ ↑+O ₂ ↑;

6. Formation of nitrogen: C+O ₂ =CO ₂ (combustion), 2C+O ₂ =2CO (incomplete combustion), C+CO ₂ =2CO (high temperature), 4CO+2NO ₂ ==N ₂ +4CO ₂ (platinum wire catalysis);

7. Formation of alumina: 2Al(OH) ₃ =Al ₂ O ₃ +3H ₂ O (high temperature);

8. Copper reduction reaction: CuO+CO=Cu+CO ₂ (high temperature);

9. Aluminum nitride synthesis reaction: Al ₂ O ₃ +3C+N ₂ =2AlN+3CO.

Processing principle of the present invention:

The present invention uses a combination of physics and chemistry to process waste lithium batteries. First, the waste lithium batteries are disassembled to obtain positive and negative current collectors and diaphragm paper. The diaphragm paper can be sold directly, and then the positive and negative current collectors are broken separately to obtain positive and negative current collectors. Negative current collector crushed material; pyrolyze and sieve the positive current collector crushed material to obtain metal aluminum and waste positive electrode powder.

Add sodium hydroxide to the waste positive electrode powder to remove impurities, sodium hydroxide and aluminum react to form sodium metaaluminate solution, filter and separate pure positive electrode powder, add a small amount of dilute hydrochloric acid to the filtrate, not too much, and react to form aluminum hydroxide precipitate and chlorine sodium chloride solution. The separated aluminum hydroxide is filtered again and mixed with graphite material to produce aluminum nitride, and the sodium chloride solution is electrolyzed to produce sodium hydroxide for recycling, and the metal aluminum is sold directly. The crushed material of the negative current collector is washed with water, sieved, and press-filtered to obtain metallic copper and graphite powder, and the metallic copper is sold directly. Add dilute nitric acid to graphite powder to remove impurities, react to form copper nitrate, filter and separate copper nitrate solution and graphite material, graphite material and aluminum hydroxide are mixed to form pellets, and copper nitrate is respectively put into a tube furnace for high-temperature roasting to obtain aluminum nitride Powder.

In the stage of high-temperature synthesis of aluminum nitride: the low-temperature section is used to decompose copper nitrate into copper oxide and nitrogen dioxide, and the carbon monoxide produced by part of the carbon reacts with nitrogen dioxide to generate nitrogen, and platinum wire is added in the furnace body as a catalyst. Alumina is decomposed into alumina powder, and graphite, alumina and nitrogen are synthesized into aluminum nitride powder in the high temperature section, which also reduces the subsequent carbon removal process.

The beneficial effects of the present invention are as follows:

In the process of synthesizing aluminum nitride of the present invention, no additional delivery of nitrogen is needed, and the reaction process is in a self-sufficient state, so that the reaction is more stable, and the purity of the formed aluminum nitride is high. The method of the invention directly treats the positive and negative electrodes separately, which reduces the difficulty of subsequent impurity removal. For the preparation of alumina, the chemical dissolution method is used instead of physical crushing, and it is more beneficial to the removal of impurities in the positive electrode powder, because on the one hand, the aluminum source is obtained from the positive electrode powder, and on the other hand, the impurity metal aluminum is removed from the positive electrode powder. It is more conducive to the subsequent wet leaching of the positive electrode powder, so it is more conducive to the removal of impurities. The method of the present invention does not produce waste residue and waste water as a whole, has relatively stable reaction, simple operation process, high resource recovery rate, and can be put into production later.

Description of drawings

Fig. 1 is the process flow chart of embodiment 1 of the present invention.

Detailed ways

The conception and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts belong to The protection scope of the present invention.

Example 1

The preparation method of aluminum nitride of the present embodiment comprises the following steps:

(1) Take the single waste lithium battery and disassemble it to obtain the separator paper, positive current collector and negative current collector;

(2) The positive and negative current collectors are crushed separately, the crusher is shear-type crushing, the screen aperture is 1 cm, and the crushing time is 2 minutes to obtain the positive current collector crushed material;

(3) Put the crushed material of the positive current collector into the horse boiling furnace, control the temperature at 450°C, keep it warm for 1 hour, and finally sieve to obtain metal aluminum and positive electrode powder. The sieve is selected to be 10 mesh, and the impurity content Al in the positive electrode powder is measured to be 11.34%. , Cu is 0.01%, Ni in metal aluminum is 0.26%, Co is 0.12%;

(4) Take 300g of positive electrode powder, add 300ml of 15g/L sodium hydroxide, the liquid-solid ratio is 1:1, the stirring speed is 300r/min, stir for 20min, filter, the filter residue enters the wet leaching, and the mass fraction of the filtrate is 50% hydrochloric acid, do not excessive, until the precipitation occurs, stop adding hydrochloric acid when the precipitation begins to dissolve, then filter to obtain aluminum hydroxide precipitation and sodium chloride solution, and the sodium chloride solution is electrolyzed to produce sodium hydroxide for use in step (1) ;

(5) Take 500g of negative current collector crushed material, add water and wash at a liquid-solid ratio of 1:1, stir at 200r/min, wash for 5min, sieve to obtain metal copper and graphite slurry, press filter graphite slurry, and measure the filter residue Obtain impurity copper content to be 9.82%, aluminum content to be 0.03%, add mass fraction in the slag and be 50% nitric acid 100ml, stirring reaction 10min, until impurity copper all dissolves, pressure filtration separates, respectively obtains copper nitrate solution and graphite material, metal Copper can be sold directly;

(6) Mix the graphite material in step (5) with the aluminum hydroxide precipitate in step (4) at a mass ratio of 1:2, put them into the pelletizer, the size of the sphere is 1mm, and mix the copper nitrate solution and aluminum hydroxide by The mass ratio is 2:1 and the sphere is put into the same tube furnace respectively, and a small amount of platinum wire is put into the furnace. The high-temperature roasting design is divided into three stages. At 1000°C, keep warm for 2 hours, and the three stages are as follows: the temperature is controlled at 1400°C, and the holding time is 6 hours, and finally aluminum nitride powder and copper oxide are obtained.

After the above steps, the separator paper, metal copper, metal aluminum, positive electrode powder and aluminum nitride powder are obtained. Among them, the separator paper, metal copper, metal aluminum, copper oxide and aluminum nitride are sold directly, and the positive electrode powder can enter the wet process. leach.

Example 2

(1) Take the waste lithium battery and disassemble it to obtain separator paper, positive current collector and negative current collector respectively;

(2) Break the positive and negative current collectors separately, the crusher is shear crushing, the aperture of the screen is 1cm, and the crushing time is 2min;

(4) Take 250g of positive electrode powder and add 200ml of 10g/L sodium hydroxide, the liquid-solid ratio is 1:1.2, the stirring speed is 300r/min, stir for 20min, filter, the filter residue enters wet leaching, and the filtrate is added with Hydrochloric acid, do not excessive, until precipitation produces, stop adding hydrochloric acid when precipitation begins to dissolve, then filter, obtain aluminum hydroxide precipitation and sodium chloride solution, sodium chloride solution is electrolyzed, and production sodium hydroxide is used for step (1);

(5) Take 800g of negative current collector broken material, add water to wash at a liquid-solid ratio of 1:1, stir at a speed of 200r/min, and wash with water for 5min, sieve to obtain metal copper and graphite slurry, press filter graphite slurry, and filter residue The measured impurity copper content is 9.18%, and the aluminum content is 0.02%. Adding 150ml of nitric acid with a mass fraction of 40% in the slag, stirring and reacting for 10min, until the impurity copper is completely dissolved, separated by pressure filtration, respectively to obtain copper nitrate solution and graphite material, Metal copper can be sold directly;

(6) Mix the graphite material in step (5) with the aluminum hydroxide precipitate in step (4) at a mass ratio of 1:2, put them into the pelletizer, the size of the sphere is 1mm, and mix the copper nitrate solution and aluminum hydroxide by The mass ratio is 3:1 and the sphere is put into the same tubular furnace respectively, and a small amount of platinum wire is put into the furnace. The high-temperature roasting design is divided into three stages. At 1000°C, keep warm for 2 hours, and the three stages are as follows: the temperature is controlled at 1400°C, and the holding time is 6 hours, and finally aluminum nitride powder and copper oxide are obtained.

Example 3

(4) Take 500g of positive electrode powder, add 300ml of 20g/L sodium hydroxide, the liquid-solid ratio is 1:1.7, the stirring speed is 300r/min, stir for 20min, filter, the filter residue enters the wet leaching method, and the mass fraction of the filtrate is 50% hydrochloric acid, do not excessive, until the precipitation occurs, stop adding hydrochloric acid when the precipitation begins to dissolve, then filter to obtain aluminum hydroxide precipitation and sodium chloride solution, and the sodium chloride solution is electrolyzed to produce sodium hydroxide for use in step (1) ;

(5) Take 1000g of negative current collector broken material, add water to wash at a liquid-solid ratio of 1:1, stir at a speed of 200r/min, wash with water for 5min, sieve to obtain metal copper and graphite slurry, graphite slurry press filter, and filter residue The measured impurity copper content is 10.08%, the aluminum content is 0.04%, the slag is added the nitric acid 200ml that mass fraction is 40%, stir reaction 10min, until impurity copper all dissolves, press filtration separates, obtain copper nitrate solution and graphite material respectively , metal copper can be sold directly;

(6) Mix the graphite material in step (5) with the aluminum hydroxide precipitate in step (4) at a mass ratio of 1:1, put them into the pelletizer, the size of the sphere is 1mm, and mix the copper nitrate solution and aluminum hydroxide by The mass ratio is 2:1 and the sphere is put into the same tube furnace respectively, and a small amount of platinum wire is put into the furnace. The high-temperature roasting design is divided into three stages. Control at 1200°C, keep warm for 2h; the third stage is; the temperature is controlled at 1600°C, keep warm for 6h, and finally remove carbon at 500°C under air circulation, keep warm for 1h to obtain aluminum nitride powder.

Comparative example 1

The preparation method of this comparative example aluminum nitride powder comprises the following steps:

(4) Take 250g of positive electrode powder and add 200ml of 10g/L sodium hydroxide, the liquid-solid ratio is 1:1.2, the stirring speed is 300r/min, stir for 20min, filter, the filter residue enters wet leaching, and the filtrate is added with Hydrochloric acid, do not overdose until precipitation occurs; stop adding dilute hydrochloric acid when the precipitation begins to dissolve, and then filter to obtain aluminum hydroxide precipitation and sodium chloride solution, and electrolyze the sodium chloride solution to produce sodium hydroxide for front-end use;

(5) Take 800g of negative current collector broken material, add water to wash at a liquid-solid ratio of 1:1, stir at a speed of 200r/min, and wash with water for 5min, sieve to obtain metal copper and graphite slurry, press filter graphite slurry, and filter residue The measured impurity copper content is 9.18%, and the aluminum content is 0.02%. Adding 100ml of nitric acid with a mass fraction of 40% in the slag, stirring and reacting for 10min, until the impurity copper is completely dissolved, separated by pressure filtration to obtain copper nitrate solution and graphite material respectively. Metal copper can be sold directly;

(6) Mix the graphite material in step (5) with the aluminum hydroxide precipitate in step (4) in a mass ratio of 1:2, put them into the pelletizer, the size of the spheres is 1mm, put the spheres into the tube furnace, Sufficient nitrogen is filled, and the high-temperature roasting design is divided into three stages. The first stage is: the temperature is controlled at 200°C, and the heat preservation is 1h; the second stage is: the temperature is controlled at 1000°C, and the heat preservation is 2h; After 6 hours, aluminum nitride powder is finally obtained.

After the above steps, the separator paper, metal copper, metal aluminum, positive electrode powder and aluminum nitride powder are obtained. Among them, the separator paper, metal copper, metal aluminum and aluminum nitride are sold directly, and the positive electrode powder can be wet leached. Nitric acid Copper requires additional processing.

Element content test results:

Use ICP (inductively coupled plasma spectroscopic analysis) to detect the key element content in the aluminum nitride products prepared by various embodiments of the present invention and comparative examples, the results are shown in the following table 1

The elemental content in the aluminum nitride product prepared by table 1 embodiment and comparative example

It can be seen from the data in the table that the product produced by this process has high purity, strong feasibility, and low impurity content; in the comparison ratio, it can be concluded that the raw material ratio is still affected by nitrogen, and the carbon in the early stage has been completely burned away, resulting in nitrogen and oxidation in the later stage. Aluminum reacts, and the reaction is incomplete, and the impurity content is high, and the remaining copper nitrate in this process needs additional processing.

Table 2 Composition content of copper oxide

It can be concluded from Table 2 that the copper oxide heated by copper nitrate is highly feasible to be reduced to metallic copper, the product has good purity, high selling value, and strong recyclability. The copper nitrate solution in the comparative example is not treated, and the impurity content of the substance is high, the direct sale value is low, additional processing is required, and it is toxic, harmful and explosive, and it is easy to cause a particularly large hidden danger if it is not handled in time.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and within the scope of knowledge of those of ordinary skill in the art, various modifications can be made without departing from the spirit of the present invention. Variety. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict.

Claims

A kind of preparation method of aluminum nitride is characterized in that, comprises the following steps:

(1) Add sodium hydroxide solution to the waste positive electrode powder for reaction, and separate solid and liquid to obtain sodium metaaluminate solution and positive electrode powder;

(2) adding an acid to the sodium metaaluminate solution for reaction, separating solid and liquid to obtain aluminum hydroxide precipitation;

(3) washing the negative current collector, screening, solid-liquid separation, taking the solid phase and adding nitric acid to react, solid-liquid separation, to obtain graphite material and copper nitrate;

(4) The aluminum hydroxide precipitation described in step (2) is mixed and granulated with the graphite material described in step (3), and then the copper nitrate described in step (3) is added to mix and roasted to obtain aluminum nitride and copper oxide .
The preparation method according to claim 1, characterized in that, in step (1), the waste positive electrode powder is disassembled and crushed from waste lithium batteries to obtain positive and negative current collector broken materials and separator paper, and then the positive collector The fluid crushed material is pyrolyzed and sieved to obtain metal aluminum and waste positive electrode powder.
The preparation method according to claim 2, characterized in that the pyrolysis temperature is 400-600° C., and the pyrolysis time is 0.5-1 h.
The preparation method according to claim 1, characterized in that, in step (1), the liquid-solid ratio of the sodium hydroxide solution and the waste positive electrode powder is 1: (1-3) L/g.
The preparation method according to claim 1, characterized in that, in step (2), the acid is one of hydrochloric acid and nitric acid; when the acid is hydrochloric acid, after the solid-liquid separation in step (2), , to obtain aluminum hydroxide precipitate and sodium chloride solution.
The preparation method according to claim 5, wherein the sodium chloride solution is electrolyzed to produce sodium hydroxide, which is returned to step (1) for use.
The preparation method according to claim 1, characterized in that, in step (3), the mass fraction of the nitric acid is 30-50%.
preparation method according to claim 1, is characterized in that, in step (4), the mass ratio of described copper nitrate and aluminum hydroxide is (1-3):1.
The preparation method according to claim 1, characterized in that in step (4), the calcination is carried out in three stages, the temperature of the first stage of calcination is 200-400°C, and the time of the first stage of calcination is 0.5-2h The temperature of the second stage of calcination is 1000-1200°C, and the time of the second stage of calcination is 1-3h; the temperature of the third stage of calcination is 1400-1600°C, and the time of the third stage of calcination is 5-8h.
The preparation method according to claim 1, characterized in that, in step (4), the roasting reaction process also includes adding a catalyst for catalysis; the catalyst is platinum wire.